Filter devices of a general type incorporating two filter membranes of equal size on oppositely disposed sides of a membrane support are well known in the art as shown, for example, by U.S. Pat. No. 3,730,353. The purpose of using the two filter membranes, instead of only one, is to double the available filtration area without commensurate increase in the size of the filtration device. However, such filter devices have heretofore consisted of assemblies of three or more components, in addition to the two filter membranes, and at that with the geometry of the components and assemblies being such as to involve difficulties and expense in manufacture without compensating increase in filtration performance or effective filter life.
The objective realized by the present invention is a compact filter device which provides the desired increased filtration surface area by the incorporation of two membranes and which can be manufactured at relatively low cost using, in addition to the two membranes, only two components, each a plastic molding, which can be readily bonded together.